Typically, when a glass substrate is in manufacture, marks will be formed on the substrate, and the marks can be used for confirming an ID of the substrate and can also be used for aligning; usually, these marks are higher than the surface of the substrate; when a rubbing alignment process is performed on the substrate, due to influence of the height of the marks, damage may be caused to a rubbing cloth, for example, the hairiness of the rubbing cloth, which is apt to cause undesirable linear rubbing defect, and generate relative undesirable alignment defects such as rubbing mura.